A small-sized boat is known where a lower part of the body is formed by a hull, an upper part of the body is formed by a deck, a jet pump is attached to the rear of the hull and water is sucked from a suction opening at the bottom of the body by driving the jet pump by an engine and which is glided by jetting the sucked water backward.
JP-A No. 89395/2003 discloses a jet pump mounting structure of a small-sized boat where a pump case is provided to the rear of a hull, a thrust plate is provided to a front wall of the pump case and a jet pump is provided to the thrust plate.
In the jet pump mounting structure of the small-sized boat, the jet pump is held in a desired position by providing the thrust plate to the front wall of the pump case and providing the jet pump to the thrust plate, water is jetted from a nozzle of the jet pump, and the jetted water is used as the driving force.
A hull and a deck forming the body are made of resin and are normally molded by injection molding.
FIG. 6 is an explanatory drawing for explaining a process in which a hull of a conventional type small-sized boat is molded.
A fixed mold 101 and a movable mold 102 of a mold 100 are clamped and a cavity 103 is formed. Melted resin 105 is supplied into the cavity 103 via an injection passage 104 from a direction shown by an arrow “a”. The melted resin 105 in the cavity 103 is solidified to form the hull 106. The movable mold 102 is moved in a direction shown by an arrow “b”, the mold 100 is opened, and the hull 106 is released from the opened mold 100.
As for the hull 106, as a front wall 108 of a pump case 107 is substantially vertically formed, no draft angle with the front wall 108 is formed. Therefore, when the hull 106 is released from the mold 100, the hull 106 may not be able to be smoothly released from the mold 100, particularly from the movable mold 102 and it prevents the hull 106 from being easily manufactured.
Therefore, it would be beneficial to provide jet pump mounting structure of a small-sized boat where a jet pump can be mounted in a desired position and the manufacture can be facilitated.